Biomedical subjects

A Murakami

Publications and source records attributed to A Murakami.

At least 271 records · Page 15Linked to original sources

PubMed1992

Hydroxyl radical formation by UV-irradiated epidermal cells.

To elucidate the mechanism of sunlight-induced skin damage, guinea pigs were exposed to UV light (280-320 nm, UV B, 4 J/cm2) and a homogenate of the epidermis was examined by means of the thiobarbituric acid (TBA) test. Three hours after the exposure, TBA-malondialdehyde adducts had increased while glutathione reductase activity had decreased, indicating lipid peroxidation. To detect the initial species, spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was applied to a suspension of illuminated epidermal cells (0.5 J/cm2). An ESR signal obtained only with irradiation comprised a 1:2:2:1 quartet [a(N)= a(beta H) = 1.49 mT] attributable to a spin adduct of hydroxyl radicals. These results suggest that sunlight exposure of skin may lead to hydroxyl radical generation and simultaneous lipid peroxidation.

Animals↗

PubMed1992

Biochemical characteristics of thylakoid membranes in chloroplasts of dark-grown pine cotyledons.

Japanese black pine (Pinus thunbergii) cotyledons were found to synthesize chlorophylls in complete darkness during germination, although the synthesis was not as great as that in the light. The compositions of thylakoid components in plastids of cotyledons grown in the dark and light were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of polypeptides and spectroscopic determination of membrane redox components. All thylakoid membrane proteins found in preparations from light-grown cotyledons were also present in preparations from dark-grown cotyledons. However, levels of photosystem I, photosystem II, cytochrome b([ill])/f, and light-harvesting chlorophyll-protein complexes in dark-grown cotyledons were only one-fourth of those in light-grown cotyledons, on a fresh weight basis. These results suggest that the low abundance of thylakoid components in dark-grown cotyledons is associated with the limited supply of chlorophyll needed to assemble the two photosystem complexes and the light-harvesting chlorophyll-protein complex.

Journal Article↗

PubMed1992

Effects of calphobindin II (annexin VI) on procoagulant and anticoagulant activities of cultured endothelial cells.

Effects of human placental calphobindin II (CPB-II) on the protein C activation and prothrombin activation on the cell surface of cultured calf pulmonary arterial endothelial cells have been investigated. CPB-II inhibited thrombin generation by factor Xa bound to the surface of the cultured endothelial cells in a dose-dependent manner. The amount (IC50) of CPB-II causing the inhibition at 50% was estimated to be approximately 10 nM. CPB-II was found to be ineffective, however, in the protein C activation by thrombin-thrombomodulin (TM) complex on the cell surface. Assay using purified TM revealed that CPB-II was able to exhibit the inhibitory potency for the protein C activation exclusively in the reconstituted system with negatively charged phospholipids. These results suggest that the neutral phospholipids participate in the protein C activation through the thrombin-TM system on the endothelial cell surface. The ability of CPB-II to inhibit procoagulant activity without affecting anticoagulant activity on the cultured endothelial cells is probably related to its potential physiological function, while it is able to exert various degrees of influence upon these activities in blood coagulation by interacting with negatively charged phospholipids in vitro.

Amino Acid Sequence↗

PubMed1992

Chalcone tetramers, lophirachalcone and alatachalcone, from Lophira alata as possible anti-tumor promoters.

Two chalcone tetramers were isolated as inhibitors of Epstein-Barr virus (EBV)-activation induced by a tumor promoter, teleocidin B-4, from a medicinal plant in tropical west Africa, Lophira alata (Ochnaceae). One of them was identified as lophirachalcone. The other, named alatachalcone, was new, and the structure was determined by spectral properties. Both compounds also showed potent inhibitory activities against teleocidin B-4-induced inflammation on mouse ear. In an initiation-promotion experiment on mouse skin, alatachalcone (16 nmol) significantly inhibited tumor promotion caused by 12-O-tetradecanoylphorbol-13-acetate (TPA, 1.6 nmol).

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1992

Essential oil phenyl propanoids. Useful as .OH scavengers?

In order to search for radical scavengers which could be used as raw materials for cosmetics, phenyl propanoids (eugenol, isoeugenol, dehydrodieugenol, dehydrodieugenol B and coniferyl aldehyde) were examined for their hydroxyl radical (.OH) scavenging ability. A Fenton system was used to produce .OH. In order to see scavenging by these phenyl propanoids, competition reactions between a spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and these phenyl propanoids for .OH were studied. The relative yield of the spin adduct of .OH (DMPO-OH) was measured by electron spin resonance spectroscopy. The approximate rate constants of the reactions between these phenyl propanoids and .OH estimated by measuring the reduced height of the ESR signals of DMPO-OH were found to be at least in the order of 10(9) M-1 s-1 (diffusion-controlled). Also, using the TBA tests, the reactions between .OH and several compounds reactive with .OH were investigated in the presence of the phenyl propanoids and it was found that the phenyl propanoids compete with such reactive compounds for .OH. These results indicate that these phenyl propanoids can be used as antioxidants for skin damage perhaps caused by .OH generated by UV-light.

Animals↗

PubMed1992

Short-term microgravity to isolate graviperception in cells.

In the fall of 1991 a series of drop-tower experiments in ZARM (Bremen) was devoted to behavioural responses of unicellular organisms to step-type transition from normal gravity to microgravity. Modules for simultaneous 4-fold video-recording were incorporated into the flight capsule. In the course of 25 flights, 100 sets of experiments, each holding 100 to 200 cells, were flown under various conditions with a technical success rate of 94% and about 80% of the cells accessible to evaluation in the laboratory. A major goal of the experiments was the assessment of parameters of locomotion (velocity, orientation) in the absence of the gravity vector. The data show that in two species, Paramecium and Loxodes, the properties of steady-state microgravity-swimming correspond to horizontal swimming under 1g-conditions. In a third species, Didinium, microgravity-swimming velocity exceeds 1 g-horizontal rates. The data are in agreement with an electrophysiological hypothesis of graviperception in cells.

Animals↗

PubMed1992

Interaction of antisense DNA with nucleic acids/proteins.

In order to study interaction of various types of labeled antisense DNAs were prepared. Fluorescein and 2,2,6,6-tetramethypiperidine-N-oxyl were the label molecules, which were introduced to 5'-end of oligonucleotides and their analogs. Interactions of labeled antisense DNAs with nucleic acids or proteins such as HSA, HIG and TF, were studied by UV, fluorescence depolarization spectroscopy, and ESR spectroscopy. Hybrid formation of antisense DNAs with oligonucleotides in solution could be monitored by the increase in fluorescence anisotropy (r) and by intensity change in ESR spectra. When phosphorothioate type antisense molecules anchoring fluorescein (F-OPT) were mixed with proteins, r drastically increased, whereas ODN slightly increased. These results suggest that OPTs have much more affinity for proteins than ODNs.

Blood Proteins↗

PubMed1992

Syntheses and properties of fluorescent labeled oligonucleotides containing deoxyethenoadenosine at 5' end.

The fluorescent labeled oligodeoxyribonucleotides which contain deoxyethenoadenosione (d epsilon A) at their 5' end were prepared by treating CPG bound oligonucleotides with 5'-DMTr-deoxyethenoadenosine-3'-H-phosphonate. The hybrid formation of d epsilon A-oligonucleotide with its complementary DNA was studied by fluorescence spectroscopy. The fluorescence of d epsilon A in a single strand was largely quenched by stacking interaction with the base at 3' position. When d epsilon A-oligonucleotides hybridized with their complementary strands, relative fluorescence quantum yields (Qrel) against d epsilon A changed in specific manners. These results suggest that d epsilon A-oligonucleotides are applicable to study the local structure of DNA in solution.

Base Sequence↗

PubMed1992

Separation and characterization of diastereoisomeric oligonucleotide.

For developing the antisense method, two types of oligonucleotides suitable for antisense molecules were explored for their essential properties. One is oligonucleoside phosphorothioate, and all their possible R/S diastereoisomers were separated and purified by reversed phase liquid chromatography. Isolated diastereoisomers have been investigated for the correlation between their configuration and hybridization manner. Separation, R/S characterization and spectroscopical properties of these oligonucleotides will be discussed.

Chromatography, High Pressure Liquid↗

PubMed1992

Effects of base damages on DNA replication--mechanism of preferential purine nucleotide insertion opposite abasic site in template DNA.

DNA polymerase preferentially inserts purine nucleotides opposite non-instructive lesions such as abasic sites during DNA replication. In order to elucidate the mechanism of the preferential insertion, a DNA template containing a model abasic site and primers containing 4 different nucleotides (A,G,C,T) at primer terminus were synthesized. The stability of the primer terminus nucleotide placed opposite the abasic site was evaluated on the basis of its sensitivity to 3'-5' exonuclease associated with DNA polymerase.

DNA↗

PubMed1992

NMR studies on solution structure of single-stranded oligonucleotides causing line broadening.

Unusual line broadening of 1H-NMR lines attributable to the proton (8H) of guanine residues was observed for all tetradeoxyoligonucleotides tested here which have a specific base sequence of dGXXG (X = A or T). For the same samples, line broadening was also obtained in the 31P-NMR spectra. These broadened signals did not become sharp up to 60 degrees C. This unusual spectral phenomenon has been attributed by 2D-NMR and differential NOE to the compact solution structure of the oligonucleotides.

Magnetic Resonance Spectroscopy↗

PubMed1992

Sequence-specific DNA recognition by basic peptides.

A chiral template with C2 symmetry has been used for modeling a dimeric interface of DNA binding protein. An oligopeptide derived from the basic region of MyoD, a recently described "helix-loop-helix" class of DNA binding protein, has been tethered to the template. Among the four models which differ in chirality and polarity with respect to the arrangement of two subunits, only one dimer model with right-handed and C-terminus to C-terminus arrangement of the peptide subunits binds DNA containing native MyoD binding sequence.

DNA↗

PubMed1992

[Magnetic resonance imaging: evaluation of the Blalock-Taussig shunts and anatomy of the pulmonary artery].

The morphology and circulation of the pulmonary arteries and shunt vessels were evaluated by magnetic resonance imaging (MRI) in 8 patients with cyanotic heart disease after a Blalock-Taussig shunt operation. Their ages ranged from one month to 17 years. MRI permitted assessment of the size and patency of the Blalock-Taussig shunts, as well as the size and morphology of the pulmonary arteries in all patients. Measurements of the vessel diameters on MRI correlated well with the angiographic measurements (main pulmonary artery, r = 0.98; right pulmonary artery, r = 0.98; left pulmonary artery, r = 0.98; and Blalock-Taussig shunt, r = 0.97). MRI successfully imaged 3 of 4 shunt obstructions and 3 of 4 pulmonary stenoses with high resolution. In assessing peripheral pulmonary stenosis or obstruction, MRI was superior to echocardiography, the latter being unable to image peripheral pulmonary arteries satisfactorily. We concluded that MRI is an excellent noninvasive method for serially evaluating the anatomy and function of Blalock-Taussig shunts and pulmonary arteries, which is particularly useful for children with cyanotic congenital heart disease.

Adolescent↗

PubMed1992

Monomer-dimer equilibrium of nitroso-aromatic spin trap 3,5-dibromo-4-nitrosobenzenesulfonic acid, sodium salt (DBNBS), in aqueous solution.

3,5-Dibromo-4-nitrosobenzenesulfonic acid, sodium salt (DBNBS), which is widely used as a spin trap in biological systems, was allowed to form the monomer-dimer equilibrium in aqueous solution, and its equilibrium constant (Kc) was determined by NMR measurement and visible spectrum analysis. The Kc values obtained from the two different methods were virtually identical and evaluated as 1.3 x 10(-3) mol dm-3 at 25 degrees C. Further, the molar extinction coefficient of DBNBS monomer (epsilon 760) was determined to be 34 dm3mol-1cm-1. The present results indicate that only a minor portion (ca. 20%) of dissolved DBNBS (10 mmol dm-3) is practically capable of spin trapping under the conditions most widely used in biological studies.

Benzenesulfonates↗

PubMed1992

Comparison of 2,5,5-trimethyl-1-pyrroline-N-oxide (M3PO) and 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin traps.

2,5,5-Trimethyl-1-pyrroline-N-oxide (M3PO) and 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) were examined for their potential as spin traps used in biological samples, and the results obtained for M3PO and M4PO were compared with those of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) reported previously. The rate constants for the reactions of M3PO and M4PO with hydroxyl radicals were in the same order of that constant of DMPO. The hyperfine splitting constants of M4PO spin adducts were as informative as those of DMPO adducts. In the presence of ferric ions, M3PO and M4PO formed 2-hydroxy-2,5,5-dimethyl-1-pyrrolidinyloxy (M3PO-OH) and 2-hydroxy-3,3,5,5-tetramethyl-1-pyrrolidinyloxyl (M4PO-OH), respectively, by the nucleophilic addition of a water molecule, as we have already reported for DMPO. M4PO-OH was subjected to oxidation by ferric ions with a rate much slower than that for DMPO-OH, while M3PO-OH was not. The results indicate that M4PO is a spin trap suitable for biological applications and that nitrones having a methyl group at C2 represent improved spin traps.

Cyclic N-Oxides↗

PubMed1992

[A successful operative case of congenital mitral stenosis associated with double outlet right ventricle, patent ductus arteriosus, persistent left superior vena cava and severe pulmonary hypertension in adult].

A 29-year-old woman, who was diagnosed as congenital mitral stenosis associated with DORV, PDA, PLSVC and severe pulmonary hypertension, was reported. The mitral valve, consisting of leaflet dysplasia, shortened and thickened chordae tendineae, obliteration of interchordal spaces, under-development of papillary muscle, and stenotic supravalvular membrane, was replaced with 25 SJM prosthesis. Simultaneously, patch closure of VSD and intrapulmonary direct closure of PDA was performed. Her postoperative course was uneventful and systolic pulmonary arterial pressure fell down from 95 mmHg to 56 mmHg. She is doing well after correction. To our knowledge, this is very rare corrective case with congenital mitral stenosis in adult to be reported in the literature in Japan.

Adult↗

PubMed1992

Nonsense-codon mutations of the ornithine aminotransferase gene with decreased levels of mutant mRNA in gyrate atrophy.

A generalized deficiency of the mitochondrial matrix enzyme ornithine aminotransferase (OAT) is the inborn error in gyrate atrophy (GA), an autosomal recessive degenerative disease of the retina and choroid of the eye. Mutations in the OAT gene show a high degree of molecular heterogeneity in GA, reflecting the genetic heterogeneity in this disease. Using the combined techniques of PCR, denaturing gradient gel electrophoresis, and direct sequencing, we have identified three nonsense-codon mutations and one nonsense codon-generating mutation of the OAT gene in GA pedigrees. Three of them are single-base substitutions, and one is a 2-bp deletion resulting in a reading frameshift. A nonsense codon created at position 79 (TGA) by a frameshift and nonsense mutations at codons 209 (TAT----TAA) and 299 (TAC----TAG) result in abnormally low levels of OAT mRNA in the patient's skin fibroblasts. A nonsense mutation at codon 426 (CGA----TGA) in the last exon, however, has little effect on the mRNA level. Thus, the mRNA level can be reduced by nonsense-codon mutations, but the position of the mutation may be important, with earlier premature-translation termination having a greater effect than a later mutation.

Adult↗

PubMed1991

Tumor cytotoxic factor/hepatocyte growth factor from human fibroblasts: cloning of its cDNA, purification and characterization of recombinant protein.

Two different forms of cDNA for F-TCF were isolated from cDNA library prepared with mRNA from human embryonic lung fibroblast, IMR-90 cells. One of them was completely identical to the cDNA for placenta type hepatocyte growth factor (HGF) and the other one was a variant cDNA for the HGF with a deletion of 15 base pairs in the coding region. The cDNAs were expressed in CHO cells and recombinant proteins were purified and characterized. The deleted form of recombinant F-TCF (rF-TCF) was slightly lower in heparin affinity than the intact form. Both rF-TCFs showed almost same dose-response curves for cytotoxicity on Sarcoma 180 or Meth A sarcoma cells. Dose-response curves for the stimulation of DNA synthesis in rat hepatocytes were also almost same before reaching maximal activity at 12.5 ng/ml but significantly different at higher concentrations. The deleted form of rF-TCF maintained maximal activity in the dose range of 12.5 to 100 ng/ml, although the intact form decreased the activity dose-dependently at more than 25 ng/ml. This suggests that the deletion of five amino acids results in a conformational change which alters heparin binding and hepatocyte growth stimulating activities.

Amino Acid Sequence↗